Starter spring



Nov. 19, 1935. J. A. CHARTER STARTER SPRING Filed April 5, 1935 Patented Nov. 19, 1935 UiTE STATES STARTER SPRING James A. Charter, Chicago, 111., as'signor to Charter Drive, Inc., Chicago, 111., a corporation of Illinois Application April 5, 1935, Serial No. 14,757

3 Claims.

My invention relates generally to starter springs, and more particularly to springs for use in starters wherein the spring presents a yieldable driving connection and operatively 5 functions to cause movement of a pinion or driving member.

The spring of the present invention was disclosed in my application, Serial No. 640,483, filed October 31,1932, which has since matured into Patent No. 1,979,869. The subject matter set forth in said patent was limited to an engine starter including the combination of a double spring Construction, a driving member or pinion, and associated driving shaft unit. The present application, however, is directed to the spring structure per se. The spring of the present invention is of the type adapted to be coupled with a driving pinion which is designed to be axially shifted along a drive shaft unit. The convolutions of the spring not only serve to absorb shocks resulting from the engagement of the pinion with the gear of the engine to be driven, but are so spaced as to present ahelical way for receiving and guiding a tracker extending outwardly from the drive shaft unit. The rotative movement of the tracker within the helical way causes the spring and pinion as a unit to be shifted axially toward or away from the engine gear.

My invention relates more specifically to a spring structure of a construction which is adapted to withstand severe strains and stresses, or, in other words, heavy load conditions when in use. To this end my invention contemplates the use of a double strand spring structure, the convolutions of which are adjacently positioned, thereby enabling a smaller sized wire to be formed into a helix, and at the same time obtain the required strength.

Still more specifically, my invention contemplates a heavy duty type of spring of the double strand construction having hooks at the free extremities of the strands which are adapted to be received by complementary recesses in a driving pinion.

My invention also contemplates a double spring construction, as set forth above, wherein one extremity thereof is provided with a loop for efiectively engaging the tracker of the drive shaft unit in establishing a yieldable driving connection between said unit and the engine gear.

The foregoing and numerous other objects and advantages will be more apparent from the following detailed description when considered in connection with the wherein- Figure 1 is a perspective view of a spring which is representative of one embodiment of accompanying drawing,

the invention; 5.

lustrate the arrangement of the juxta-positioned 10- spring strands and the helical way presented therebetween.

Referring now to the drawing more in detail wherein like numerals have been employed to designate similar parts throughout the various l5 figures, it will be seen that my invention contemplates a spring structure designated generally by the numeral II], which is comprised of a plurality of double strand convolutions l2 spaced apart axially to present a helical way M. The 2() spring is preferably of flat elongated cross section and the two strands are juxta-positioned, as shown in the drawing. The free extremities of the strands are provided with identical hook portions 16. These hook portions are formed by 25 bending the spring stock axially and then circumferentially so as to provide an open side or area 18 adapted to freely receive the part or structure of the part with which the spring is to be coupled. It will be noted that the termina- 30 tion or free end 20 of the hooks 16 extends in a circumferential direction, and that said hooks are diametrically positioned to afford a balanced spring structure. The opposite extremity of the spring structure is provided with means in the 35 form of a loop 22, and this loop 22 traverses the helical way M, and hence is adapted to impinge or be impinged by a tracker (not shown) movable in the helical way l4, thereby establishing a yieldable driving connection.

From the foregoing description it will be un-, derstood that my invention contemplates an improved double-strand spring construction, which is provided with a pair of open type hooks 0r coupling means at the free extremities of the strands to materially facilitate the coupling or connection of the spring with a rotary driving element such as a pinion (not shown). In fact, by employing a double spring construction equipped with the open type bends, hooks, or coupling means, as above described, the necessity of employing bolts, studs, etc., for securing the spring in place, is avoided. In other words, by providing the free extremity of each strand with an axially extending portion and a circumferb5 entially extending portion to form an open hook, the practical application of the double spring arrangement in the field is greatly enhanced. The diametrical positioning of the hooks not only provides a balanced spring structure, but also serves to more uniformly apply the driving load to the pinion or part with which the spring is coupled, particularly when the loop 22 is engaged for establishing a yieldable driving connection as above mentioned.

From the foregoing description it will be apparent that I prefer to form the hooks l6 by bending the stock axially in an outward direction, namely in a direction away from the spring structure. Stating it in another way, the coupling means or hooks are formed by bending the free ends of the spring stock in a direction away from the loop 22. In a double spring structure of my improved design, the free extremities of the spring do not terminate at the same point, but rather at diametrically opposite points. Thus it will be seen that the strand which, at the hooked end of the spring structure, constitutes the inner strand, continues helically and circumferentially beyond the free extremity of the outer strand to present a diametrically positioned hook or coupling means. My improved spring structure may be made helically right or lefthand to accommodate the particular environment in which it is to be used. In one spring the hook portions bend circumferentially in one direction, and in the other spring they open circumferentially in the opposite direction. The coupling means or hooks enable the spring and part driven thereby to be coupled together without the aid of auxiliary fastening devices and the like, and, although the hooks are open sided, these openings extend circumferentially and hence enable the entire spring structure to be positively secured against axial displacement with respect to the part with which it is coupledfor example, a driving pinionand also enable the spring to be positively rotated as a unit with said pinion.

Attention is also directed to the fact that the open sided bends or hooks, open circumferentially in the same direction. In other words, the circumferentially extending portions 20 of the hooks are bent circumferentially in the same direction, as viewed from the left of Figure 1. It might also be said that, when viewed from the left of Figure 1, and not considered in a circumferential direction, the hooks are bent in opposite directions and are diametrically positioned. While one particular embodiment of the invention has been disclosed, it should be understood that other modifications and changes are contemplated without departing from the spirit and the scope of the appended claims.

Having thus described my invention, What I claim as new and desire to secure by Letters Patent is:

1. A coiled spring for forming a driving connection in an engine starter of the type in which a pinion and spring connected therewith move together as a unit, said spring including a double strand of coiled spring wire, the convolutions of said double strand being axially spaced to provide a helical way, means traversing said helical way toward one extremity of said coiled spring providing an abutment surface adapted to be engaged for driving purposes, and a coupling means provided at the free extremity of each strand at the opposite end of said coil spring, each of said coupling means including an axially extending portion and a circumferentially extending portion providing an open sided bend, the bend on each coupling means opening outwardly and in the same circumferential direction, whereby said bends may be received by a part to be driven by said spring.

2. A coiled spring for forming a driving connection in an engine starter of the type in which a pinion and spring connected therewith move together as a unit, said spring including a double strand of coiled spring wire, the-convolutions of said double strand being axially spaced to provide a helical way, means traversing said helical way toward one extremity of said coiled spring providing an abutment surface adapted to be engaged for driving purposes, and a coupling means provided at the free extremity of each strand at the opposite end of said coil spring, said coupling means being diametrically positioned with respect to each other and each coupling means including an axially extending portion and a circumferentially extending portion pro-' viding an open sided bend, the bend on each coupling means opening outwardly and in the same circumferential direction, whereby said bends may be received by .a part to be driven by said spring.

3. A coiledspring for forming a driving connection in an engine starter of the type in which a pinion and spring connected therewith move together as a unit, said spring including a double strand of coiled spring wire, the convolutions of said double strand being axially spaced to provide a helical way, means traversing said helical way toward one extremity of said coiled spring providing an abutment surface adapted to be engaged for driving purposes, and a coupling means provided at the free extremity of each strand at the opposite end of said coil spring, each of said coupling means comprising open hooks extending outwardly from the coils of said spring and opening circumferentially in the same direction, whereby said hooks may be received by complementary recesses in the part to be driven by said spring.

JAMES A. CHARTER. 

